I. Field of the Invention
The present invention relates generally to surgical instruments and, more particularly, to a keratome for use in eye surgery.
II. Description of the Prior Art
In cataract surgery, it is necessary to first remove the opacified lens from the human eye. Thereafter, the natural lens is typically replaced by an artificial lens which restores vision to the patient.
In cataract surgery, a sclera dissector is first utilized to form a small tunnel in the sclera at a position spaced a few millimeters outwardly from the cornea of the eye. In doing so, the scleral dissector forms a small flap in the sclera.
After the tunnel is formed in the sclera, a small keratome is first used to complete the incision within the tunnel and into the anterior chamber of the eye. Where the natural lens of the eye is removed by phacoemulsification, a keratome having a width of approximately three millimeters completes the incision under the sclera flap and into the anterior chamber of the eye. This relatively small incision is sufficient to permit the insertion of the phacoemulsifier into the eye in order to remove the natural lens of the eye. Following removal of the natural lens of the eye, the phacoemulsifier is likewise removed from the eye.
In order to thereafter implant an artificial lens into the eye, it is necessary to widen the incision in the eye to a width of 4.0 millimeters or more in order to implant the lens.
With reference now to FIGS. 1-3, in order to widen the incision to permit the implantation of the artificial lens, it has been the previously known practice to use a keratome 10 having a width of 4.0 millimeters or more which is inserted into the sclera tunnel 12 (FIG. 2) and into the anterior chamber of the eye.
These previously known keratomes 10 typically comprise an elongated handle 14 having a flat blade 16 at one end. A generally V-shaped cutting edge 18 faces away from the handle 14 and cuts through the sclera under the cornea as the keratome 10 is inserted through the scleral tunnel 12 and into the anterior chamber of the eye.
One disadvantage off these previously known keratomes 10, however, is that the blade 16 is planar in shape. As such, as shown in FIG. 3, the blade creates a flat cut 20 in the sclera 22. The sclera 22, however, is curved as indicated by the radius of curvature 24 of the eye in the area immediately adjacent the cornea 26 so that the thickness of the sclera at the center of the blade cut is larger than the thickness of the sclera along the sides of the blade cut. Consequently, when the keratomes 10 having relatively wide blades 16 are used to perform the final incision into the eye, it is possible for the side edges of the keratome blade 16 to protrude through and cut the top surface of the sclera 22 due to the interference created between the curved sclera 22 and the flat blade 16 of the keratome 10.